The use of pressure-sensitive adhesive tape for the purpose of sealing boxes, and more specifically box flaps, is generally known. Moreover, it is known that cartons or boxes which are continuously moved along a conveyor can be automatically sealed by such adhesive tape.
Box sealing machines have been developed for applying lengths of tape to boxes as they are moved through such machines in a continuous manner. Moreover, such box sealing machines are known to be provided as part of a packaging line where the boxes are fed continuously to the box sealing machine from which the sealed boxes are further conveyed for further processing, such as palletizing, shipping, etc. Boxes are typically sealed on one or more sides, and such box sealing machines typically provide taping heads of a number corresponding to the number of box sides to be sealed. The taping heads may be arranged to seal the top and bottom box flaps, opposite side flaps, or any combination thereof.
Such box sealing machines, like any other machine within the packaging line, when down, have the potential to slow down or even stop the entire packaging line. Thus, it is beneficial to minimize such down time. Unless the adhesive tape is supplied to the box sealing machine by a continuous tape supply, that is of indefinite length, the box sealing machine will need to be stopped on a regular basis to change tape rolls. Minimizing other down time is highly desirable.
It is not only important to minimize machine down time, it is also important to minimize improper taping and sealing of boxes. Further in this regard, it is desirable to detect any improper taping or other errors within the packaging line so that it can be corrected as soon as possible. Of course, the longer that it takes to detect such error, the more boxes that are improperly sealed and which must be redone.
The monitoring of equipment in general as well as the monitoring of product exiting any production line for quality purposes is well known. Such monitoring includes the use of a wide variety of inspection systems which rely on many different kinds of sensors depending on the object being monitored. Typical sensors include cameras, optical sensors, mechanical sensors, magnetic sensors, electrical sensors, and the like, which are typically provided as part of a controlled system which includes a feedback loop or circuit which may control such processing equipment. Moreover, it is generally known that if certain errors are detected, machines may be actually shut down until a correction is made. Examples of labeling machines having sensing systems which disable certain machine functions upon the detection of a missing label are described in U.S. Pat. No. 4,687,535 to Voltmer and U.S. Pat. No. 3,989,574 to Evans.
With regard to box sealing machines, it is well known to use a variety of sensors, such as mechanical switches, optical sensors, photo cells, electrical switches, and the like to control the taping operation of a box driven through such machine. Typically, such sensors detect the position of the box as it is moved through the machine and controls specific taping operations based on the detected box position. Examples of such taping machines including control sensors can be found in U.S. Pat. Nos. 4,846,921 to Lerner et al., 4,836,873 to Mitanihara et al., U.S. Pat. No. 4,640,731 to Lerner et al., U.S. Pat. Nos. 4,585,504, 4,554,042 and 4,538,398 to Marchetti, and U.S. Pat. No. 4,548,022 to Yaklia. The sensing systems of these machines, however, are not provided with the sensing error conditions. Moreover, they do not provide a feedback for disabling any function of the machines.
One such box sealing machine which includes a sensor for detecting an error condition is that described in U.S. Pat. No. 4,855,006 to Marchetti. In this machine, a control system is provided to sense the tape feed so that it is possible to stop the machine if the tape feed ceases. More specifically, the control system is a pneumatic system comprising a pneumatic valve which is responsive to a cam which is rotated by the tape as it is applied. The valve further controls a timer which generates a warning signal for each occasion in which the time interval is longer than a predetermined limit. Additionally, the taping head includes a second pneumatic valve which activates the system upon the presence of a box within the machine at the point of the taping head. Thus, when a box is present, and if the application of tape is not sensed by the first sensor, an error condition is detected and a warning is made which may include machine stoppage. Lastly, a third pneumatic valve sensor is provided which detects when a supplied tape roll is nearly depleted. The pneumatic sensing system of the Marchetti device is limited in that it senses or detects an error to occur only when a box is present and tape is not dispensed. It would not sense other potential error conditions, such as may occur when tape is being dispensed while a box is no longer present, which may occur by a failure to cut an applied length of tape.